The 37-year-old and her partner, television presenter Clarke Gayford, have not yet revealed the sex of the baby, which was due on Sunday.

While determined to keep working until the day, Ms Ardern has for weeks now been the target of an avalanche of personal questions, parenting advice and intense media attention.

She's expected to briefly speak to reporters after the birth.

Although she will become the first elected world leader to take maternity leave - and only the second to have a child while in office - Ms Ardern has played down the significant global attention she's received as a role model.